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Updated: Jun 20, 2026

Glass-Based Devices to Generate Drops and Emulsions
Published on: April 5, 2022
Generation and mixing of subfemtoliter aqueous droplets on demand
Jianyong Tang1, Ana M Jofre, Rani B Kishore
1Physics Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
Abstract:
We describe a novel method of generating monodisperse subfemtoliter aqueous droplets on demand by means of piezoelectric injection. Droplets with volumes down to 200 aL are generated by this technique. The droplets are injected into a low refractive index perfluorocarbon so that they can be optically trapped. We demonstrate the use of optical tweezers to manipulate and mix droplets. For example, using optical tweezers we bring two droplets, one containing a calcium sensitive dye and the other calcium chloride, into contact. The droplets coalesce with a resulting reaction time of about 1 ms. The monodispersity, manipulability, repeatability, small size, and fast mixing afforded by this system offer many opportunities for nanochemistry and observation of chemical reactions on a molecule-by-molecule basis.

